Cycle News - Archive Issues - 1990's

.RACER TEST Troy Corser's and John Kocinski's Factory Ducati 996cc Superbike Comparison Ducati 996cc Superbike Technical Development t's exactly 10 years ago that the Ducati otto valvole bined to deliver this extra power reliably. Ducati continfirst appeared in public, at the 1986 Bol d'Or 24 Hour ues to experiment with valve sizes and piston design in race in France - an improbable, yet romantic exten- pursuit of higher revs, but the best engines retain the sion to the Italian manufacturer's then-quirky V-twin 37mm inlet/31 rom exhaust valve format and three-ring desmo lineage. Improbable, because the idea that a Omega pistons used before. A key factor in obtaining extra power with the bigger twin-qrlinder motorcycle could ever seriously compete with the high-revving fours from Japan - even with a 25 engine was a larger airbox, homologated via the 916SP, percent capacity advantage and 20 percent lower weight the space for which was created by moving the stain1esslimit - seemed unlikely, and romantic because the lusty steel header tank for the water radiator further forward, boom of a big V-twin was a welcome addition to the thus usefully adding to front weight bias, always a probSuperbike class, even if it had no chance of winning. lem with the L-twin Ducati, and one reason the Nice background music, though. Well, here we are a decade later and history records show that Massimo Bordi and his team of clever engineers have hqd the last laugh. They did what their Japanese rivals thought impossible, and turned their no-hoper V-twin desmo into the dominant four-stroke race bike of the modem era. Keeping ahead of the game meant that 750cc Ducati otto valvole prototype which debuted in the Bol d'Or a decade ago swiftly increased to 851cc in capacity to compete with the 750 fours, then to 888cc, 926cc, 955cc and now at last this year to 996cc in works form, as Ducati finally took full advantage of the lOOOcc capacity limit for twin-cylinder superbikes. Meanwhile, though, the minimum weight limit for twins has also increased gradually, from the 308 pounds it started out at back in 1988, to 319, then 341, and now for 1996 to 356 pounds - for the first time, the same as the fours. If you want an idea of how big an extra penalty that last jump is, go ·to the supermarket and stick 15 one- swingarm is still in magnesium rather than alloy, even pound bags of sugar in a grocery bag, then pick it up. with the extra IS-pound weight penalty this season. The Heavy, isn't it. airbox is fed by bigger-ducts than. before, all of which is Faced with this extra weight burden for the '96 sea- crucial to performance with the jumbo 996cc motor, son, and the growing threat from its Japanese rivals, which by definition pumps more air than its smallerespecially Honda, Ducati's engineers responded in two bore predecessor. After close inspection by the FIM at ways, applying Formula-Orie car-type technology to Hockenheim, World Superbike technical supreme Steve max out the cylinder bore another 2mm, then go for revs, Whitelock approved the modification, which certain in spite of the increased piston speeds this entails. But at other teams had openly questioned. But the extra power delivered by increasing the bore, a time when an averagely trick 3000cc F-1 car engine like the Jordan's V-10 Peugeot measures 70 x 42 mm and narrowing the power band and going for revs brought spins to 16,400 rpm with the aid ofpneumatic valve gear accompanying overheating problems - one reason the - to deliver positive valve operation - the 98 x 66 mm compression ratio remains at just 12:1. Ducati got an Ducati 996 has proved it can handle 12,000 rpm and - early warning of this when it cost Troy Corser and the more - thanks to mechanicaJJy obtaining the same effect factory their long-awaited victory in the Daytona 200 in via desmodromics. March. Winter testing on slower tracks like Misano and But the effect is the same: radical camshaft design even Mugello hadn't prepared them for this problem permitted by doing away with valve springs aJIows with the bigger engine in warmer temperatureS on faster higher revs and more extreme valve timing, in turn tracks like the Florida Speedway and Monza. delivering more·power. A lot more. Even on the Ducati So by the time the World Superbike season began, the factory's notoriously stingy dyno, the current 996cc works Superbike delivers 149 bhp at 11,300 rpm at . the gearbox, 7 bhp more than last year and equating to around 160 bhp on a more generous engine brake. Frankly, it seems improbable that any other manufacturer will ever be able to equal Ducati's power output allied to ridability with a twin-cylinder Superbike, unless they too adopt positive valve operation. Right, Harley? Would you agree, Aprilia? To achieve this impressive output, Ducali made a number of key improvements for 1996 to the eightvalve motor, starting with bigger homologated throttle bodies measuring 48mm at the throttle butterfly, rising to 54mm at the trumpet (up from 46/ 50mm in '95) for the Weber / Marelli EFI, which uses revised differential mappIng for front and rear cylinders. Fuel pressure was increased from 4.5 to 5.0 bar via the regulator, while the exhaust system was upsized from 52mm to 54mm diameter, with only the rear section At the limit: Ducatl has maxed out displacement under the in titanium - the front pipes are stainless steel, to help present superblke rules. All that's left now is more revs. load up the front-end weight bias. A new inlet camshaft helped proVide extra midrange '95 radiator had been replaced by a double-sta.ck one po.wer between 8,000-9,500- rpm compared to the '95 sourced from Japan's leading Ducati tuners Team Founbike, while constant experimentation with cylinder-head dation, based on that used on the NSR250 Honda GP porting and combustion shape delivered more top-end bike! A bigger oil radiator with an extra two rows of power as well as increased torque. cooling was also fitted. Together with new Ohlins triple Stronger crankcases made feasible by the increased clamps for the 46mm upside-down forks, allowing the weight limit, titanium Pank! rods and titanium valves 320mm cast iron Brembo brake discs to be spread 28mm which give the rockers an easier life at high revs - always further apart, primarily to improve braking performance a critical factor on a' desmodromic engine, especiall y by lowering disc temperatures but also to improve airwith eight separate rockers per cylinder head - all com- flow to the radiators, this problem has just about been I • resolved - for now. The '97-model 916 street bike will have extra slots cut in the bodywork to aid hot-air extraction, but thermodynamics will playa vital part in future Ducati R&D. The extra 15 pounds Ducati was obliged to add for this season were spread around the bike, aidlng robustness and reliability as well as frontal weight bias. A host of minor details contributed to the weight gain, from making the gear selector drum in steel rather than Ergal aircraft aJJoy, to heavier triple. clamps, steel bolts and fasteners rather than aJJoy or titanium ones, alloy engine covers instead of magnesium ones, and so forth. But check out the stripped-down bike, and you'll see .carbon fiber is still' used anywhere aft of the center line, to aid that front-end weight bias so ,ritical to optimum handling. And of course, carbon is retained for the airbox, too, which plays a vital role in stiffening the chassis. Both this and the cast-magnesium swingarm are unchanged for '96. . The series of high-profile engine problems suffered by the Promotor team and Troy Corser in particular have thrown a question mark over the reliability of the 996cc motor, and it's certainly true that during the course of the season, Ducati has had to take risks in order to keep that vital half-step ahead of Honda's resurgent RC45. But it has to be said that Kocinski and Hodgson haven't suffered anything like the same problems with their similar Team Ferrari bikes, nor has PierFrancesco Chili with his privateer jumbo desmo, which uses works cylinders and pistons in engines built by top Ducati gt1!ti Pietro Gianesin. Normal engine life is 620 miles, at which point the motor is rebuilt with new cylinders, pistons, rockers, valves and crankcases. The small 10-man engine team headed by race engineers Franco Fame and Ivo Bertoni in the Ducati race department built an amazing 44 engines for the first five rounds of the '96 season! Hard though it must be for the Promotor team to accept. it seems just the luck of the draw th.at theY've had the problems they've had with relatively fresh or even brand-new engines at crucial moments when headed for victory. If not for engine failures at Brands Hatch and Sugo, Troy Corser would have been set firmly on the path for championship victory just past the halfway point in the season. Instead, the Australian had to fight, for all the way to the end. The 996cc version of its otto valvole 916-based racer represents Ducati's final hand of cards in Superl;>ike racing's Last Chance Saloon: they've beaten the weight rap, but now they've used up all· th.eir aces, having maxed out the capacity and got radical with the power curve. They still have some good cards to play, the best of which will be the further application of F-l car technology in pursuit of .even more revs - expect 13,000 rpm as the next milestone in desmo V-twin engine performance. But at the end of the day, it's time for Ducati to do what aJJ its Japanese rivals have done at least once in· the past decade that the Italian V-twin has been winning races, and that is switch to a new engine design. Nobody knows this better than Ducati technical boss, LUigi Mengoli, and the head of the Reparto Corse, Claudio Domenicali, and such an engine has already existed on paper for at least one year. , But Ducati's cash crisis meant that the money didn't exist to put it into metal - until now. The American buy-in to the Italian marque must surely generate the needed development funds to fast-forward the next generation of eight-valve desmo engine, still a 90degree V-twin, but reputedly with an extractable gearbox and the cylinders rotated backward on the crankcases to deliver a more compact design that won't compromise weight distribution and chassis layout. Take a look at the new Honda VTR1000 for an idea of the cylinder format. But it'll be at least three years before we see the new desmoquattro Superbike in action. Until then, the frustration of Ducati's rivals at being constantly at least half a step behind the level of development of the Italian bikes shows no sign of having a permanent cUre - yet. LAST ::..-C Ii A"NCE· ·SALOON· \0 0'\ 0'\ T'""'i ~ T'""'i l-< Q) "S Q) :> o Z 14

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